A study involving half a million people by Harvard and Peking university researchers has found those who eat spicy foods every day have a 14 per cent lower risk of death than those who eat it less than once a week.

The pattern was similar in both men and women.

A love of chilli foods was also linked to a lower risk of death from cancer as well as ischaemic heart and respiratory system diseases.

The researchers enrolled 487,375 people in China aged 30 to 79 years between 2004 and 2008.

"During a median follow-up of 7.2 years, we documented 11,820 deaths among men and 8404 deaths among women," Lu Qi from Harvard University and Jun Lv from Peking University said in their paper, published in The BMJ.

"Compared with participants who ate spicy foods less than once a week, those who consumed spicy foods six or seven days a week showed a 14 per cent relative risk reduction in total mortality."

Participants with a history of cancer, heart disease, and stroke were excluded from the study, and factors such as age, marital status, level of education, and physical activity were taken into account.

The authors warned against drawing definitive conclusions from the observational study and called for more research that may "lead to updated dietary recommendations and development of functional foods".

Earlier research suggests the beneficial effects of spices and their bioactive ingredient capsaicin include anti-obesity, antioxidant, anti-inflammation and anti-cancer properties.

Veteran nutritionist Rosemary Stanton, a visiting fellow at University of NSW, said spicy foods were also known to be more satisfying to the appetite.

"When people eat bland food, they overeat, which is known to have a negative impact on long-term health," she said.

But Dr Jimmy Louie, a nutritional epidemiology expert at the University of Sydney, warned the public about getting too excited about the results, as such studies did not prove causality.

"You shouldn't look at the results of this epidemiological study and say, 'This is what I should do'. This is not the intention of the study. The study shows an association of two factors, it doesn't prove which one causes which," he said.

"The next step is to run a randomised trial," he said. "This is a lot more expensive."

In an editorial in The BMJ, nutritional epidemiology expert Nita Forouhi from the University of Cambridge said the study did not take into account dietary habits linked with eating spicy foods, the degree of hotness of the foods, and the impact of associated drinking habits.

"Future studies should explore if confounding or effect modification by other drinking habits might play a part, as it is highly likely that drinks such as water or different types of tea are consumed in greater amounts among those with a greater chilli intake," she said.

"Concurrently there is evidence for an inverse association between tea consumption and mortality."